Inertia switch



Aug. 3, 1943.

K EDSTROM INERTIA SWITCH Filed Sept. 21, 1939 INVENTOR. 164m. A. 0; TRON Patented Aug. 3, 1943 INERTIA SWITCH.

Karl A. Edstrom, Denver, Colo., assignor to The Electric Alarm Company, Inc., Denver, Colo.

Application September 21, 1939, SerialNo. 295,851

2' Claims.

This invention relates to improvements in theft alarms and has reference to an improved signal control mechanism responsive to mechanical vibrations, and relates more particularly to an improved vibration responsive switch device for use in a mechanism of the general type disclosed and claimed in United States Letters Patent No. 1,983,932, issued December 11, 1934.

Devices of the type to which this invention relates are primarily intended for use on automobiles and must therefore be so constructed that they will not be rendered inoperative by reason of the constant vibrations to which they are subjected during the operation of the automobile.

This invention relates more particularly to an improved switch mechanism employed for closing an electric circuit when the device is vibrated and which serves to initiate the functioning of a signal or alarm.

The principal object of this invention is to produce a vibration-responsive switch which is mounted on a flexible resilient pivot that will not bind or wear to any appreciable extent and which permits th inertia member carried thereby to operate freely.

Other objects and advantages reside in details of design and construction which will be more .fully disclosed in the following description and in the drawing wherein like parts have been similarly designated and in which:

Figure 1 Ban elevation view of the device, the electrical wires, battery and horn being shown diagrammatically;

Figure 2 is a section taken on line 22, Figure 1, and shows the manner in which the inertia member, of the vibration-responsive switch, is supported;

Figure 3 is a section taken on line 33, Figure 1;

Figure 4 is a section taken on line 44, Figure 2; and

Figure 5 is a section Figure 1.

In the example taken on line 5-5,

herewith illustrated, that embodies the present invention, reference numeral 6 designates the back of a sheet metal box whose ends have been designated by numeral 1 and sides by numeral 8.

Supported on the back is a base 9 of insulating material, such as hard rubber, fiber or Bakelite. The several parts are attached to the base by screws, or other suitable means, in such a way that they are electrically insulated from each other.

Reference numeral l0 designates an electromagnet and numeral II the pole piece thereof. An armature I2 is attached to the lower end of a fiat spring l3, whose upper end is clamped between the vertical limbs of two angular brackets l4 whose bases I5 are secured to the insulating base 9, thus forming a pendulum.

Located below the brackets I4 is a U-shaped plate l6 having at each end a vertical arm I! to which an adjusting screw 18 is threadedly connected. Plate is is also provided with two vertical arms l9 whose outer sides are engaged by the screws l8. Each arm [9 is provided with a contact point 29. The spring arm [3 of the pendulum is provided with contact points that are opposite to the contact points 20, but normally out of engagement with them. The contact points 20 are so adjusted with respect to the contact points on the pendulum that when the latter vibrates beyond a certain minimum amplitude, they will establish electrical connection with contacts 20.

A battery B, or other source of electrical current supply, has one pole grounded at G and the other pole connected with one terminal of an electric switch S by means of a conductor D. The other terminal of the switch is connected to the horn C by means of a conductor E while conductor F extends from the horn to the bracket 15. A conductor H grounds the plate IE3 at G.

It is now evident that each time the contact point on the pendulum one go a contact point as the horn will sound. It i o evident that if the electromagnet ill is moan arily energized, it will attract the armature 52 ad immediately release the same thereby permitting it to vibrate freely and actuate the circuit to the horn.

In order to so energize the electromagnet H), the circuit to said electromagnet is c ntrolled by a vibration-responsive switch mechanism which will now be described, and which embodies the improvement over the disclosure of the patent above identified.

A bracket having ecured to the base cated subs 2' said base. to the a.

a base 2! and an arm 22 is 9 so that said arm 22 is 10- ly midway between the ends of nent-shaped plate 23 is fastened a s of bolts and positinned with its l- .121 to the base. The tips 25 t beyond the chord side thereof, and the latter has a centra-l'notch 26.

A steel band or ribbon 2? encircleg the plate .23, and is held. position on the edge of the plate by washers 28 secured to the plate by rivets 29. A switch arm 36 mounted on the ribbon 21 and is provided at each of its ends with a able .L l i trgyrnagnet almost immed' tely y/ith the result L always remain in equilibrium regardless of the inclination of the base 9.

weights i.

V The upper surface of one of the weights 8i,

isprovided with a contact which is nor mall-y spaced short distance from a contact point 353 carried by aiiiex ble arm of bracket fastened t i? an When the ice is vibrated bri contact po- V on weight A engagement with the contact poi L is established from th h t G, through the SlfiCtl gized thereby a at s 1; thereby clos ng t circuit to the horn I v is fli rand releases the armature {2, w ion in and which con es to vibrate ior s or the current to the ho n is made and broken several times.

If the vibration of the device ceases, the electromagnet will remain Lie-energized and the operation of the horn will cease as soon as the pendulum i2i3 ceases to vibrate beyond a j inin u n amplitude. if the vibration of the d vice is repeated, the operation described will also Joe repeated.

The switch S is so located that only those initiated will know its position, and .th'ereiore; if an unauthorized person attempts to drive a car provided with this alar-rn, thehorn will continue to sound a succession of short blasts will attract the attention of the policelo r passersby.

. he m a p ded f h esn s n 9f th The torsion sites? Q? the pivot serves to stabilize the arm'iiil and' switch arm 3! gives the latter a maximum freedom of movement and ofiers the minimum resistance to such movement. movement permits the contacts to have relative movement which keeps them clean and assures an electrical connection at'each contact. The band 27 has a tendency to hold the switch arm in a given position because it acts like a torsion s in ti e? th ti is? t e sr i ii arm has no fllGtlOIL' it cannot gum and bind on account of lack of lubrication.

Extensive tests have shown that the 'means illustratedin the drawing, and described herein "has given reliable service, and has required no Witch attested ne it Cent adjustment. V V

l he example ofreduction to practice of the n ive concept, as herein illustrated is not intended to express or imply any limitation to the present invention, the scope 2? were i a rea i y mea s lair was t is invention are run accpmp n on-ar a es ve TH, e; 1P1 occur t ed ne, 1 2 fi i y made within tne scope bf ne appended clairns,

a an

aal' seiiie e sa iali wa v H a e. hereon .Q iQQ RQ Eia f a resilient ribbon providing a torsion pm, 11!) pe ted p pissi a ia a inertia giii i the ribbon fa ivqia an. in i wit an inertia element having mas 12915 9 929? at one end of the switch arm, a second inertia m t h ili siasamaii as m positioned adjacent the 91 m an 9? 5 ly- WD arm, a springruigfid electricaloomlii tor Resitioned against the arm adjacent its pivotal axis,

,, an electrical contactor positioned .0r 1 the switch remote from its pivotal axis, and another Hilatively stationary electrical contact-tor positioned in space-' relationship to the contaotor, on h switch arm and adjacent thereto iorgcontact -tnerewitn when theswitoh arm is moved.

2. An-inertiaswitch compi'ising a base, a segment-shaped upport on the base'having achordlike boundary along one side thereof and having projections extending beyond sai'd chord-like ioned' at opposite ends thereof, a

I on'providin'e torsion pivot supported on said projections and extending substantiai ly around said support, meanspn the support for holding said ribbon on the support, an inertia actuated switch ar n attached nar its center of mass to the ribbon for pivotal angul r movement therewith, an inertia elementhaving mass positioned at one end c if th'switc lfi ant, a

the

tactor tio'ned sp'a'c relationship 'oontactor on the arm ridaeigaaeia thereto i041 lai relies it l an i i moved The freedom of s in ta s eissie i r adva ta e i 

